package zk.weart.util.file;

import java.io.*;
import java.util.ArrayList;
import java.util.List;

/**
 * @Auther:
 * @Date: 2018/12/5 11:14
 * @Description:
 */
public class FileReadUtils {

    public static String readFileByBytes(String fileName) {

        String fileContent = null;


        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
        InputStream in = null;
       
        try {
            System.out.println("以字节为单位读取文件内容，一次读多个字节：");
            // 一次读多个字节
            byte[] tempbytes = new byte[100];
            int byteread = 0;
            in = new FileInputStream(fileName);
            FileReadUtils.showAvailableBytes(in);
            // 读入多个字节到字节数组中，byteread为一次读入的字节数
            while ((byteread = in.read(tempbytes)) != -1) {
                outputStream.write(tempbytes, 0, byteread);
            }
            fileContent =  outputStream.toString("utf-8");

        } catch (Exception e1) {
            e1.printStackTrace();
        } finally {
            if (in != null) {
                try {
                    in.close();
                    outputStream.close();
                } catch (IOException e1) {
                }
            }
        }
        return  fileContent;
    }

    /**
     * 以字符为单位读取文件，常用于读文本，数字等类型的文件
     */
    public static void readFileByChars(String fileName) {
        File file = new File(fileName);
        Reader reader = null;
        try {
            // 一次读一个字符
            reader = new InputStreamReader(new FileInputStream(file));
            int tempchar;
            while ((tempchar = reader.read()) != -1) {
                if (((char) tempchar) != '\r') {
                    System.out.print((char) tempchar);
                }
            }
            reader.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
        try {
            // 一次读多个字符
            char[] tempchars = new char[30];
            int charread = 0;
            reader = new InputStreamReader(new FileInputStream(fileName));
            // 读入多个字符到字符数组中，charread为一次读取字符数
            while ((charread = reader.read(tempchars)) != -1) {
                // 同样屏蔽掉\r不显示
                if ((charread == tempchars.length)
                        && (tempchars[tempchars.length - 1] != '\r')) {
                    System.out.print(tempchars);
                } else {
                    for (int i = 0; i < charread; i++) {
                        if (tempchars[i] == '\r') {
                            continue;
                        } else {
                            System.out.print(tempchars[i]);
                        }
                    }
                }
            }

        } catch (Exception e1) {
            e1.printStackTrace();
        } finally {
            if (reader != null) {
                try {
                    reader.close();
                } catch (IOException e1) {
                }
            }
        }
    }

    /**
     * 以行为单位读取文件，常用于读面向行的格式化文件
     */
    public static void readFileByLines(String fileName) {
        File file = new File(fileName);
        BufferedReader reader = null;
        try {
            System.out.println("以行为单位读取文件内容，一次读一整行：");
            reader = new BufferedReader(new FileReader(file));
            String tempString = null;
            int line = 1;
            // 一次读入一行，直到读入null为文件结束
            while ((tempString = reader.readLine()) != null) {
                // 显示行号
                System.out.println("line " + line + ": " + tempString);
                line++;
            }
            reader.close();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (reader != null) {
                try {
                    reader.close();
                } catch (IOException e1) {
                }
            }
        }
    }

    /**
     * 随机读取文件内容
     */
    public static void readFileByRandomAccess(String fileName) {
        RandomAccessFile randomFile = null;
        try {
            System.out.println("随机读取一段文件内容：");
            // 打开一个随机访问文件流，按只读方式
            randomFile = new RandomAccessFile(fileName, "r");
            // 文件长度，字节数
            long fileLength = randomFile.length();
            // 读文件的起始位置
            int beginIndex = (fileLength > 4) ? 4 : 0;
            // 将读文件的开始位置移到beginIndex位置。
            randomFile.seek(beginIndex);
            byte[] bytes = new byte[10];
            int byteread = 0;
            // 一次读10个字节，如果文件内容不足10个字节，则读剩下的字节。
            // 将一次读取的字节数赋给byteread
            while ((byteread = randomFile.read(bytes)) != -1) {
                System.out.write(bytes, 0, byteread);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (randomFile != null) {
                try {
                    randomFile.close();
                } catch (IOException e1) {
                }
            }
        }
    }

    /**
     * 显示输入流中还剩的字节数
     */
    private static void showAvailableBytes(InputStream in) {
        try {
            System.out.println("当前字节输入流中的字节数为:" + in.available());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static String read(String path, String encoding) {
        String content = "";
        BufferedReader reader = null;
        try {

        File file = new File(path);
            reader = new BufferedReader(new InputStreamReader(
                new FileInputStream(file), encoding));
        String line = null;
        while ((line = reader.readLine()) != null) {
            content += line + "\n";
        }

        }catch (Exception e){
            e.printStackTrace();
        }finally {
            try {
                if (reader!=null){
                    reader.close();
                }
            }catch (Exception e){
                e.printStackTrace();

            }

        }

        return content;

    }


    public static List<String > readList(String path, String encoding) {
        String content = "";
        BufferedReader reader = null;
        List<String> list =  new ArrayList<>();
        try {

            File file = new File(path);
            reader = new BufferedReader(new InputStreamReader(
                    new FileInputStream(file), encoding));
            String line = null;
            while ((line = reader.readLine()) != null) {
                list.add(line);
            }

        }catch (Exception e){
            e.printStackTrace();
        }finally {
            try {
                if (reader!=null){
                    reader.close();
                }
            }catch (Exception e){
                e.printStackTrace();

            }

        }

        return list;

    }

    public static void main(String[] args) {
        String fileName = "C:/temp/newTemp.txt";
        FileReadUtils.readFileByBytes(fileName);
        FileReadUtils.readFileByChars(fileName);
        FileReadUtils.readFileByLines(fileName);
        FileReadUtils.readFileByRandomAccess(fileName);
    }
}
